Decontamination paste consisting of clays and microfibers and method for decontaminating a solid material using said paste

A decontamination paste consisting of:

• at least one inorganic viscosifier selected from clays, said inorganic viscosifier representing from 20% to 70% by weight of the total weight of the paste, and said inorganic viscosifier being in the form of micron- and/or nano-sized particles;
• at least one compound in the form of fibres that have a diameter from 2 μm to 10 μm and a length from 50 μm to 10 mm;
• optionally, furthermore, one or more component(s) selected from the following components:
• at least one non-ionic surfactant selected from ethylene oxide and propylene oxide block copolymers and ethoxylated fatty acids;
• at least one active decontamination agent selected from the group consisting of sodium hydroxide, potassium hydroxide, nitric acid, phosphoric acid, hydrochloric acid, sulphuric acid, hydrogen oxalates, peroxides, permanganates, persulphates, ozone, hypochlorites, cerium IV salts, hexadecylpyridinium salts, reducing agents;
• and mixtures thereof;
• at least one contaminant species extracting agent selected from the group consisting of zeolites, clays, phosphates, titanates, ferrocyanides and ferricyanides;
• at least one contaminant species chelating agent selected from the group consisting of n-octylphenyl-N,N-diisobutylcarbamoyl methylphosphine oxide (CMPO), tributyl phosphate (TBP), 1-hydroxyethane-1,1-disphosphinic acid (HEDPA), di-2-ethylhexylphosphoric acid (DHEPA), trioctylphosphine oxide (TOPO), diethylenetriamine pentaacetate (DTPA), primary, secondary and tertiary organic amines, cobalt dicarbollide, calixarenes, niobates, ammonium molybdophosphate (AMP), (trimethylpentyl) phosphinic acid (TPPA), and mixtures thereof;
• at least one colouring agent selected from organic dyes and mineral pigments;
• and the balance of solvent selected from water, organic solvents and mixtures thereof,
• wherein said decontamination paste has a viscosity greater than or equal to 100 Pa·s at 20° C. for a shear rate of less than 1 s−1.